A reclining apparatus will be described with reference to FIGS. 9 and 10. FIG. 9 is a view illustrating a configuration of a seat and FIG. 10 is a side view of a reclining apparatus for a vehicle seat of the related art.
As shown in FIG. 9, a seat 101 includes a seat cushion 102, which supports the occupant's hip, and a seat-back 103 possible to be tilted in a front-back direction with respect to the seat cushion 102 and supports the occupant's back. A reference numeral 104 denotes a reclining apparatus which is provided on a tilt shaft of the seat-back 103, and it releases and restricts the tilting of the seat-back 103.
The reclining apparatus 104 will be described with reference to FIG. 10. In FIG. 10, a hinge pin 131 is provided to stand up from a lower arm plate (a second member) 130 which is attached to the rear side of a lower arm provided in the seat cushion. A ratchet plate 132, which is attached to an upper arm provided in the side of the seat-back, is rotatably provided around the hinge pin 131. A recess having a circular surface about the hinge pin 131 is provided at a lower portion of the ratchet plate 132, wherein the circular surface has a plurality of internal teeth 133 in its circumferential direction.
A pole 134 is disposed between the lower arm plate 130 and the ratchet plate 132. The pole 134 has a circular surface that faces the circular surface 132 of the ratchet plate 132 and has a plurality of external teeth 135 that are engageable with the internal teeth 133.
The lower arm plate 130 includes guides 136 and 137, which guide the pole 134 in a radial direction of a circle about the hinge pin 131 between a locked position where the external teeth 135 are engaged with the internal teeth 133 and an unlocked position where the external teeth 135 are not engaged with the internal teeth 133.
A release arm 142 is rotatably provided around the hinge pin 131 and has an elongate hole 143, which is engaged with a pin 140 of the pole 134 passing through a circular elongate hole 132e that is formed on the ratchet plate 132 about the hinge pin 131. The shape of the elongate hole 143 is configured to have parts close to and distant from the internal teeth 133 of the ratchet plate 132. Accordingly, the elongate hole is configured such that, as the release arm 142 turns, the pole 134 is moved in a radial direction of the circle about the hinge pin 131 so that the external teeth 135 of the pole 134 is engaged with or disengaged from the internal teeth 133 of the ratchet plate 132.
A first cam 144 is rotatably attached to the hinge pin 131.
A second cam 141 is provided between the first cam 144 and an inclined surface that is opposite side to the external teeth 135 of the pole 134. The inclined surface of the pole 134 is a surface that intersects with the radial direction of the circle.
The release arm 142 is urged with an urging force in a direction, toward which the first cam 144 urges the pole 134 via the second cam 141 by a spring 150. The spring 150 is an urging means having one end portion engaged to the release arm 142 and the other end portion engaged to the lower arm plate 130.
The hinge pin 131 is formed on its end surface with a groove in which an inner end portion of a spiral spring 156 is engaged, wherein an outer end portion of the spiral spring 156 is engaged with a pin 155 having an outer end portion standing up from the ratchet plate 132, so that the ratchet plate 132 (the upper arm) is urged in a forward tilting direction.
Hereinafter, the operation of the above configuration will now be described. FIG. 10 shows a locked state where the first cam 144 presses the pole 134 down via the second cam 141, which comes into contact with the inclined surface of the first cam 144, the guide 137 and the pole 134, respectively, so that the external teeth 135 of the pole 134 is engaged with the internal teeth 133 of the ratchet plate 133 to restrict the turning of the ratchet plate 132, so that the reclining (tilting) of the seat-back 103 is to be the locked state.
In this state, when the release arm 142 that is located at a position depicted by a solid line is turned, against the urging force of the spring 150, to the position depicted by a dashed-two dotted line, the first cam 144 engaged with the release arm 142 is turned in the same direction, thereby releasing the state where the first cam 144 is pressing the pole down via the second cam 141.
Further, the pole 134 having the pin 140 which is engaged to the elongate hole 143 of the release arm 142 is also guided to the guides 136 and 137 and then is moved in the direction of the hinge pin 131. This releases the engaged state of the external teeth 135 of the pole 134 and the internal teeth 133 of the ratchet plate 132 (an unlocked state), so that the ratchet plate 132 (the seat-back 103) comes into a tiltable state.
An occupant releases a manipulating force of the release arm 142 when tilting a desired seat-back 103 to a desired tilting angle. Then, the release arm 142 returns to the position of solid line from the position of dashed-two dotted line by the urging force of the spring 150, allowing the first cam 144 to turn in the opposite direction, and to thus return to the state of FIG. 10 (see e.g. JP-A-H08-019442).